The present invention relates to a fastening device for the attaching of an electric transmitter in general.
In particular, it relates to a fastening device for attaching an electric transmitter, in particular a shear-stress transmitter, on a supporting structural part, particularly an aircraft landing gear, from which two extensions, each provided with a hole passing through it, extend at a distance from each other, each of said extensions being bolted to at least one attachment end of the transmitter provided with a hole by a threaded bolt which extends through the extension into the attachment end, and at least one nut, the attachment end lying against one side of the extension.
Such fastening devices are provided on one supporting structural part each of an aircraft landing gear for the application of an electric transmitter, in particular an inductive shear-stress transmitter, so that the transmitter gives off an electric signal corresponding to the deformation of the structural part under the load of the aircraft, it being possible to use the signal to calculate the load and the position of the center of gravity of the aircraft. A knowledge of the load and of the center of gravity is imparted in order to satisfy prescribed limit values and optimize operating variables of the aircraft, particularly velocity variables.
Up to now a fastening device of the aforementioned kind was used only for attaching a single electric transmitter between the two extensions on the supporting structural part both of which were provided with a passage hole (U.S. Pat. No. 4,269,070). A flat mounting surface of the attachment provided with hole lies in each case completely--with the exception of the hole passing through them--against a similarly flat surface of the corresponding extension. With the hole which passes through the attachment end there is aligned a passage bore in the associated extension. Each attachment end is fastened by a cap bolt whose threaded shank extends through the hole in the attachment end and the passage hole in the extension, a torque nut and a lock nut being threaded onto a threaded section of the bolt which extends out of the extension. In this way the attachment end of the transmitter is pressed between the cap of the nut and these two bolts against the flat mounting surface of the extension.
If, however, in order to satisfy modern safety requirements, two transmitters arranged in parallel to each other or their attachment ends are attachment to each extension by this known cap nut, it is not possible to loosen and replace only one of the two transmitters in case of need without, after the replacement and the renewed attachment, also recalibrating the transmitter remaining on the extension or newly applied to it. This last-mentioned transmitter is in fact necessarily also loosened upon the loosening of the cap bolt. This is true regardless of whether the attachment ends of the two transmitters are brought to rest on the same side or on different sides of the corresponding extension.
There has furthermore been proposed a holding device for the holding of two electrical transmitters, in particular shear-stress transmitters, within a tubular structural part, particularly an aircraft axle, which comprises two radially resilient holding rings which are developed with a smaller outside diameter than the inside diameter of the tubular structural part. The holding rings have radially protruding holding extensions which can rest under resilient initial stress against the inner wall of the tubular structural part. Towards the inside there extend out of each of the holding rings, in particular diametrically opposite each other, two support parts, on each of which a support element of a shear-stress transmitter can be fastened. For this purpose, a fastening bolt which extends through a hole in the support element is threaded into a threaded hole in the support part. It is not possible to bolt more than one support element for a shear-stress transmitter on one support part. Rather, for the application of each shear-stress transmitter a separate support part is provided in each of the two holding rings which are arranged spaced apart in the tubular structural part in such a manner that the shear-stress transmitters are arranged in the tubular structural part at diametrically opposite places.